This invention relates to skin cleansers. In another aspect, this invention relates to skin cleansers in bar form. In still another aspect, this invention relates to novel solid amphoteric skin cleansers.
Cleansing compositions in solid form that are intended for use on human skin are commonly called bar soaps, regardless of their chemical composition. In addition to their primary use a skin cleansers, these compositions are used as vehicles to deliver certain chemicals and drugs such as germicides and conditioners to the skin surface.
Most conventional, so-called bar soaps, used as skin cleansers, contain anionic surfactants which render them anionic in nature. These anionic cleansing compositions have certain inherent undesirable properties which limit their effectiveness in cleansing human skin as well as their usefulness as vehicles for desirable additives. For example, when used for the cleansing of human skin, all anionic bar cleansers have a relatively high irritant potential. This was shown by the article Van Scott, E. J. and Lyon J. B., "A Chemical Measure of the Effect of soaps and Detergents on the Skin," J. Invest. Dermat. 31: 199-203 (1953). Specifically, many anionic bar cleansers have limited rinsability which increases their irritant potential. In addition, anionic bar soaps are inherently incompatible with certain useful cosmetics and medicaments such as cationic germicides and conditioners that might otherwise be advantageously incorporated into a solid cleanser intended for use on human skin.
Cleansers containing amphoteric surfactants do not exhibit the undersirable properties inherent in the anionic skin cleansers. Amphoteric surfactants have been used successfully in detergents, shampoos, soaps and wetting agents. Such compositions are, however, liquids at ambient temperatures and attempts to produce solid amphoteric compositions have been unsuccessful. Heretofore, all solid amphoteric cleansing compositions have not contained commercially acceptable attributes, i.e., stability, foaming characteristics, cleansing efficiency and cosmetic appearance.